Despite evidence for a familial pattern of transmission and recent studies of depression in children, the relationship between depression in children and adults has not been systematically or prospectively investigated, and is not well understood. In addition, there is a very large overlap in the symptomatology of depression and anxiety disorders in both children and adults. These factors have impaired the ability for early identification and prevention of the development of serious depression in children and adults. The confusion between anxiety disorders and depression has also clouded efforts to identify specific etiological and pathological processes. The purpose of this study is to identify a cohort of children and adolescents who are at significant risk for developing major depressive disorders. This study will compare and differentiate children at risk for depression from those at risk for anxiety disorders. We will define the specific expression of this risk for depression and identify critical factors in the development of the disorder. In addition to their major diagnosis, we will identify specific personality and behavioral characteristics of the parents and children which affect the development of psychopathology and depression in the children. Family environmental and biological factors which may affect or differentiate the risk for depression in children will also be studied. Depressed adults from a clinic for depression and anxiety disorders, and their children will be evaluated. Diagnostic, personality and behavioral measures will be used in assessing both depressive and anxiety characteristics in order to compare them to children at risk for anxiety disorders and to normal controls. Platelet MAO and 24-hour urinary catecholamines will be measured in all subjects. Temperature circadian rhythms and GSR studies will also be completed on all subjects. A subsample of subjects will also have salivary dexamethasone suppresison tests, echocardiagrams and exercise tolerance tests. A subset of parents will additionally receive lactate infusions to assess their vulnerability to panic attacks. The results of these studies will provide critical information to improve the definition and differentiation of depression and anxiety disorders, and lead to enhanced ability for early identification of children at risk for depression. This will improve the potential for prevention of these disorders and facilitate efforts to identify specific etiological factors.